Apparatus and method for drying a solid or liquid sample

ABSTRACT

This disclosure describes a sample drying system and method that provides a high rates of evaporation and sublimation that is commonly employed in compound processing procedures. The drying increases the sample-solute concentration and removes the solvent completely to produce the dried sample as a non-volatile solute precipitate. Re-circulating of drying gas is disclosed along with a solvent cold trap.

RELATED APPLICATIONS

The present application claims the benefit and priority of the followingcommonly owned U.S. patent applications. A.) Centrifugal FractionCollection System and Method, filed Sep. 19, 2007, Ser. No. 11/901,817.B.) U.S. Provisional Patent Applications, all entitled “Device andMethod for Concentration of Solvents,” application Nos. 61/009,816,filed Jan. 2, 2008; 61/010,435, filed Jan. 8, 2008; and 61/010,670,filed Jan. 10, 2008, respectively. These applications are herebyincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the removal of solvents from a solutionto produce non-volatile material or precipitates, and more particularlyto provide high rates of evaporation and sublimation commonly applied incompound processing procedures to accelerate production of drynon-volatile materials.

2. Background Information

Compound processing to separate mixtures of chemical compounds into pureindividual components usually includes a series of sequentialdissolution process steps interspersed with drying steps. The dryingstep may only increase the concentration of a liquid or solid, but oftencomplete drying of the non-volatile precipitates is needed before are-dissolution is performed. To recover the dissolved non-volatilematerials as dry powders or to increase the concentration of compounds,three approaches are used: a) vacuum centrifuges; b) freeze drying; andc) blow down concentrators. Multi-step compound processing is timeconsuming and expensive, and drying steps are in the critical path ofany process because drying must be complete before the next step begins.Any reduction in drying time is advantageous.

Vacuum centrifuges combine a high performance vacuum pump to create verylow pressure conditions inside the chamber of a centrifuge rotor toincrease the rate at which solvent molecules can escape from the surfaceof a solution. The centrifugal force keeps solutions in their containersand prevents the violent boiling of the solution in the vacuumenvironment. A cold trap is usually configured to scavenge solventmolecules as they migrate from the higher concentration space inside thevacuum centrifuge to the low concentration space inside a solventcollection vessel in the cold trap. High performance vacuum systems areneeded to speed drying, but such vacuum systems are expensive to buy andoperate. However, these expensive, high performance systems working withwater-containing solvent (which is the most commonly occurring solventin biological samples) still only have the ability to remove water atabout 0.5 mL/hr. It would be advantageous to increase the removal rateof water in such systems.

Freeze drying is a technique chosen typically when solute molecules aresubject to degradation at temperatures above freezing or when in liquidsolutions. This process requires that the solution be frozen initially.The container with the frozen solvent material is placed in the freezedrying apparatus. A hard vacuum is pulled on the surface of solidsolution whereupon solvent molecules escape (sublime) from the solidsolution. Since sublimation is endothermic it tends to maintain thesolid frozen state of the solution. The now free solvent moleculesmigrate to and are collected in the lower concentration region of thecold trap solvent collection container. This approach retains theexpensive vacuum system while adding, in some applications, expensiverefrigeration equipment. If water is used as a solvent, the time topre-freeze compound solutions adds to the time and effort to bring thecompounds to dryness.

Blow-down concentrators create a continuous flow of a gas onto thesurface of the liquid (or solid) solution. The gas flow promotes theescape of solvent molecules from the solution container so that they canbe carried away in the flow of used gas out an exhaust port. Theblow-down unit can be located inside a fume hood so that solvent vaporsare not released to the workspace, or the exhaust port can be connectedto a cold trap to capture the solvent molecules in a container. In everycase, the exhaust outlet is directed to a fume hood. Blow-downconcentrators are configured with specific gasses which are non-reactiveto the solute compounds so that compound degradation does not occur.Nitrogen is commonly chosen to prevent degradation of potentiallyreactive compounds from oxygen in the air.

Blow down concentrators are not recommended for complete drying sincethe flow of drying gas will carry away the dry material. Using industrystandard tube (test tube-like) tube containers, known blow down drierssuggest a maximum of two (2) liters per minute of gas flow per solutiontube container. Furthermore, it is suggested that the solution not bedried to a powder, but to a more concentrated liquid state, since thisconservative gas flow rate may disturb a dry sample. The inability todry completely a sample solution reduces the performance of blow downconcentrators, and their consumption of gas (usually nitrogen) adds tothe operating costs of blow down systems.

SUMMARY OF THE INVENTION

The present invention provides a centrifuge with sample solutionscarried in tubes, and an ambient blow down gas filling the centrifugecavity. The blow down gas is forced into each tube with a centrifugalfan, and emerges carrying along solvent molecules from the sample solutebeing dried. Herein, as would be understood by those skilled in the art,“sample” as sued herein defines a precipitate in a solution that isdried to remove the solvent leaving only the dried precipitate. Anothercentrifugal fan is arranged to carry the solvent and blow down gas awayfrom the centrifuge cavity to a cold trap where the solvent collects andthe blow down gas is retrieved for reentry into the centrifuge.

In this embodiment, the centrifugal force holds the sample intact in thetube container. The present invention allows a substantially highervelocity of blow down gas to the driven into the tube container. Theeffect is that the drying rate for the sample without the use of avacuum may be five or more times higher than in known blow down driers.In addition, the centrifugal force maintains sample integrity to allowthe present invention to dry the sample completely to a dry fineparticulate powder.

In one illustrative embodiment, a fan blade structure is built onto thecentrifuge rotor. The blades end at the openings of the tube containers.A cover is placed over the fan blades and a deflector portion of thecover re-directs the gas being driven by the fan blades into the tubecontainers. In one illustrative embodiment, the gas flow rate into anyone tube container may be run upwards from 2 liters per minute and mayreach 76 liters per minute (thirty eight time the prior art gas rate) ormore.

In another illustrative embodiment, the blow down gas enters thecentrifuge cavity via a venture-type tube arrangement, and in anotherapplication the drying gas enters into a plenum with feeder tubes thatextend to the sample container openings. The drying gas is forced outthe feeder tubes and into the sample containers as the rotating samplecontainers pass by.

It will be appreciated by those skilled in the art that although thefollowing Detailed Description will proceed with reference being made toillustrative embodiments, the drawings, and methods of use, the presentinvention is not intended to be limited to these embodiments and methodsof use. Rather, the present invention is of broad scope and is intendedto be defined as only set forth in the accompanying claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention description below refers to the accompanying drawings, ofwhich:

FIG. 1A is a cross section of centrifugal drying system with fan disk 14attached to spinning centrifuge carrier 4 at height coincident withopenings 17 of containers 8 holding samples 9 to be evaporated orsublimed;

FIG. 1B is a detail drawing the blow down air flow into a tubecontainer;

FIG. 2 is a system configured for maximum drying rate where relativelydry ambient air 28 is provided to the inlet of the centrifugal fan disk14 through a venturi 27 with relatively low restriction to airflow in 28or out 20;

FIG. 3 shows a cold trap 30 has been included in a recirculation pathcomprised of outlet hose 13 and inlet hose 29 to condense solventmolecules travelling with the gas molecules around the closed-loopsystem during the drying process;

FIG. 4 is a cross section of centrifugal fan disk 14 integrated withfraction distributor subsystem 23 of centrifugal fraction collector.Atomized eluant spray 25 encounters the centrifugal fan gas-flows 18 and19 within the collection containers 8 promoting rapid dry powderformation 26 of any non-volatile material dissolved or precipitatedwithin the eluant flow stream;

FIG. 5 is a concentrator device with two levels of containers 8 and twofans 14 driven by motor 38;

FIG. 6 is a sample concentration device where blow-down gas supply isprovided by an external compressed gas supply attached to plenum 42 byfitting 41. Gas enters containers 8 as container openings 17 are sweptpast stationary nozzle array 43; and

FIG. 7 illustrates the application of the present invention to amicrotiter plate application.

DETAILED DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT

FIG. 1A shows a cross section of a typical centrifugal vacuumconcentrator where a spinning carrier 4 is contained within a closedenvironment comprising an enclosure housing 1 and a cover 2 betweenwhich is fitted a gasket 3 to prevent solvent vapors from escaping intothe user workspace. Carrier 4 is rotated at moderate speed, for example1,500 RPM, by spindle, bearing, and pulley assembly 5 driven by V-belt 6which is powered by motor pulley assembly 7.

Collection tube containers 8 are filled with the mixture 9 to be driedand inserted into sample carrier 4. The centrifugal force generated bythe spinning sample carrier 4 holds the sample material 9 within thetube containers. This force maintains sample integrity in fractioncollector applications by maximizing the capture rate of non volatilesample materials. In this drying application the yield and purity ofnon-volatile sample materials is preserved by the centrifugal forcedespite the relatively violent flow of a turbulent drying gas which thisinvention introduces into the sample containers to sweep out volatilesolvent molecules.

The sample carrier also includes a plurality of radially mountedimpeller blades 14′ to sweep gas and solvent molecules within thecentrifuge housing 1 to the circumference of the spinning samplecarrier. By providing fitting 12 and hose 13, the pressurized region gasand solvent molecules is vented out of the chamber. This reduces theconcentration of vapor molecules in the drying gas and increases itsability to accept newly evaporated solvent molecules from within thesample containers by gas flows 18 and 19. Depending upon theconfiguration of the supply of dry gas to the containment space, thesample impeller blades 11 may also serve to reduce the local pressure atthe sample surface, and similar to pulling a vacuum, facilitate theevaporation of sample solvents.

A second centrifugal planar disk fan 14, composed of radially mountedimpeller blades, is fixed to the center axis of the centrifuge. Thecircumferential ends of the blades terminate at the openings 17 of thetube containers 8. See FIG. 1B, as the centrifuge spins, gas is drawninto the fan 14 at the center shown by the flow 15. The impeller blades14′

The fan is 14, the fan blades 14.′

force 18 the gas to the perimeter of the blades where a top surface 16′is bent downwards 16 to divert the horizontal flow of gas into lowerhalf 17 a of the tube container 8. This cover 16′ may rest on theimpeller blade 14′ as they do not move with respect to each other, andthis cover 16′ may only cover the distal ends of the impeller bladesleaving an entrance opening at the center axis of the fan 14. The gasflow 18 circulates within the containers 8 across the surface 19 ofsample solutions 9 sweeping volatile solvent molecules out of the tubecontainer 8 along with the blow down gas along the flow-path 19. Thesefreed solvent molecules are then caught up in containment exhaustgas-flow 20 and ejected from the containment housing 1. As mentionedabove the blow down gas flow rate may far exceed that found in prior artsystems because centrifugal force from the spinning sample carrier ismaintaining sample integrity.

Although the fan is described above as including “impeller blades,” themechanism that drives the blow down gas into the tube containers holdingthe sample to be dried, may be described as walls, tubular structures,etc. that may be made of any acceptable material known to those skilledin the art for given applications. Moreover, the shape of the “impellerblades” as they traverse outwardly to the tubular containers may be ofvarious shapes, the flow path ways not be straight, they may curveand/or be of unequal cross sections, etc.

Users of sample concentration equipment frequently have concerns thatthe extended exposure of certain unknown (or known) solute molecules toreactive evaporative gasses (such as oxygen) will cause undesiredchemical changes (degradation) of the sample material being dried. Toconcentrate samples 9 in a particular environment, the specific desiredgas is introduced into the housing via a gas fitting 21 allow a gas-flow22. Because no other make-up gas is available, the volume of gas exitingthe housing by fitting 12 and hose 13 is necessarily equal to the volumegas introduced through fitting 21. In practice the blow down gas may beretained in the housing and recirculated multiple times to reduce theamount of desired gas which is consumed. Consequently, better economyand/or productivity can be obtained by balancing the consumption of drymake-up gas with the speed of evaporation.

Use of the centrifugal fan 14 to dry sample solutions 9 provides dryingrates which compare favorably to those obtained from traditionalvacuum-centrifuge drying systems. In this instance the complex,expensive, and maintenance-prone vacuum pump is replaced by a singlecentrifugal fan assembly 14 with no moving parts. In addition, theelimination of the vacuum pump from traditional evaporator systems maysave about $3,000 in the cost of the pump for each system and about 10KWH to 20 KWH of electricity to dry each batch of sample containers 8.

Another illustrative embodiment is shown in FIG. 2, where the cover 2has been fitted with a central venturi 27 which extends downward to apoint just above the top surface of the centrifugal fan 14. It's insidediameter is similar to that of the inlet hole in the top surface of thecentrifugal fan 14. With this configuration, ambient gas 28 is drawninto the venturi 27 by the vacuum resulting at 15 from the action of thespinning impeller blades of fan 14. If this gas is relativelyde-humidified, its ability to capture solvent molecules from the surfaceof samples 9 by gas-flows at 18 and 19 will be significantly enhanced.

A key contribution that the venturi-type port 27 makes to the dryingrate is from the introduction of drying gas with a low volatile solventmolecule content. The venturi also helps maximize the rate of drying bypreventing the induction of vapor-laden gas already in the housing backthrough the centrifugal fan 14 a second time instead of being exhaustedout of the housing through fitting 12 and hose 13.

Experimentation has demonstrated that the rate of evaporation ofsolution 9 is proportional to the velocity of gas-flow across thesurface at 18 and 19. By partially or completely blocking the flowpassages through the centrifugal fan 14 or allowing dry gas leakage fromthe fan before entering the tubular container, the rate of evaporationcan be controlled. For example a reduction by as much as 50% has beenachieved. This means of flexibility of modulating the airflows 18 and 19to achieve a specific drying rate may be advantageous to solvent dryingpractioners.

In most laboratory operations today, recovery of volatile solvents fromconcentration activities is mandatory. In larger facilities, the volumeof waste solvent is compared to the volume of solutions subjected tovarious drying processes to assure that recovery processes are effectiveand being utilized. FIG. 3 illustrates the present invention with a coldtrap 30 and cover 31. The cold trap condenses the volatile solventmolecules which have been picked up by circulating gas from the dryingsolutions 9. The efficiency of the concentration process depends largelyon a sufficiently low temperature at the interior walls of the cold trapto freeze the solvent molecules 33 and a sufficiently large cold trapvolume to assure adequate residence time of the vapor-laden circulatinggas within the cold trap so that the condensation can occur. Dried gaswithin the cold trap travels back to the centrifugal fan by flow-paths32, 34, and 35 by connecting hose 29.

If the user desires a specific gas environment during the dryingprocess, this gas is introduced to the system at fitting 21 resulting ingas-flow 22. Because this is necessarily a closed system to prevent theescape of solvent molecules from solutions 9, a vent fitting 36 isprovided behind a baffle in the cold trap 30. The rate of make-upgas-flow 22 will create an equal rate of vent gas-flow 37. Becausegas-flow 37 could still contain some uncondensed solvent molecules notcaptured in the frozen material at 33, a hose should be connectedbetween vent fitting 36 and a convenient chemical fume hood facility(not shown). A charcoal filter or other solvent scrubber may be insertedbetween the vent and fume hood.

With respect to FIG. 3 the drying performance can be increased by thejudicial application of heat to the drying process. Some compounds aretoo unstable to survive the application of any heat so considerationmust be made for the materials involved.

Irradiating the enclosed housing volume with infrared light energy towarm the samples is a common strategy familiar to those skilled in theart. Using radiation to transfer heat to the samples is practical andnecessary because of the prior art vacuum environment which existswithin typical centrifugal concentrator systems. Heat transfer byconvection is not possible in the vacuum. Heating by conduction is alsoemployed in some higher end systems, however getting the necessaryelectrical power across a rotating interface to power heaters mounted inthe rotor can be problematic.

Because the inventive system in FIG. 3 does not require vacuum tomigrate solvent molecules, convection can be used to transfer heat tothe drying samples. For example, a heating element 60 could be attachedto the housing 1 to allow heat transfer from the interior walls ofhousing 1 to the sample liquid 9 inside the tube containers 8 by meansof convection. Another location to add heat to the process would be toinsert a heat exchanger 62 in series with hose 29 to warm the gas at 34and 35 before it reenters the centrifugal fan 14.

As a practical illustration of the effectiveness of drying samples in anon-vacuum environment, consider the negative effect the prior artsample-cooling process of evaporation where sample solutions 9 freeze intheir containers 8 predicated by high vacuum, which greatly reduces therate of evaporation. Using the non-vacuum device described in thisdisclosure at drying rates up to 5-times that of typical vacuum dryingequipment, no cooling of samples was detected because the interior ofthe housing is at atmospheric pressure; full of gas molecules at roomtemperature able to replace the thermal energy lost in the samplesolutions due to evaporation. In a comparative test of a known vacuumsystem at 25 C the drying rate of water was about 0.5 mL/hour, while thedrying rate of the present invention of FIG. 3 was 2.5 mL/hour. Thedrying rate is five times (×5) that of a prior art vacuum systemresulting in five times less time to dry samples between processingsteps.

FIG. 4 of this disclosure shows centrifugal fraction collection systemhaving centrifugal fan 14 to dry samples integrated into fractiondistributor subsystem 23. The Centrifugal Fraction Collection System andMethod shown in FIG. 4 is described and incorporated by reference inPatent Application filed Sep. 19, 2007, Ser. No. 11/901,817 and inincorporated by reference Provisional Patent Application filed Jan. 9,2006, Ser. No. 60/879,385.

In this instance, the purpose is to collect and retain with high yieldthe non-volatile components of the sprayed sample material 25 fromsystem eluant tube 24 while the carrier 4 is spinning, for example, at1,500 RPM. Because the atomized volatile and non-volatile samplematerial 25 encounters the moving gas-flows 18 and 19 within container8, the greatly increased solution surface area provides almostinstantaneous drying of the non-volatile sample material which typicallyresults in collection of very fine solid sample particles 26.

As before, the centrifugal force 10 captures the dense non-volatilecomponents of the eluant spray 25 within the fraction containers 8. Theless dense volatile components are forced from the container opening 17and ejected from the containment housing 1 through port 12 and hose 13.Hose 13 is typically connected first to a cold trap (shown as 30 in FIG.3) which, through condensation of volatile gas molecules in the ejectedgas-flow, scrubs from the gas-flow stream all volatile solvent materialwhich might otherwise be released to the environment.

The integration of the centrifugal fan 14 to convert collected eluantspray 25 into dry solute material 26 provides the potential forsignificant reductions in sample preparation time and increased fractionintegrity and yield. Typically, fraction solutions are collected in anoperation separate and distinct from fraction drying. The presentdisclosure presents a device and method which combines the twooperations into one that provides the benefit of reduced totalprocessing time and reduced operator handling of samples.

The blow-down gas 18 may be selected from any suitable source given theapplication. The purpose of the centrifugal force in this invention isto capture and maintain the integrity of the samples in the containersbeing dried. If this force is sufficiently high, for example thatgenerated by 1,500 RPM, then non-volatile sample material will remaincaptured in the bottom of the sample containers nearly regardless of theflow rate of blow-down gas injected into the sample containers.

FIG. 5 shows a dryer configuration where two fans (both 14), an upperand a lower, are fixed to a shaft 39 from a motor 38 mounted to thecover of the enclosure. It is common practice to configure samplecontainers in multiple tiers to maximize the productivity of a givenconcentrator device. In FIG. 5 the second fan 14 provides a stream ofblow-down gas to the second level of sample container openings 17.

Disconnecting the centrifugal fan 14 from the spinning sample carrierpotentially allows running the fan 14 at speeds significantly higherthan the sample carrier 4. Optimum fan RPM to produce the most effectivegas flow rate might be significantly different from that desirable toachieve the centrifugal force required to maintain sample integrity.Changing the relative speeds of the centrifuge compared to the samplecarrier is well within the skill of those skilled in the art.

An alternative means to provide blow-down gas to all containers is froman external source of compressed gas as shown in FIG. 6. The userselects the gas compound and flow rate suitable for the particularapplication. The external gas supply (not shown) is connected to plenum42 at fitting 41. The gas pressurizes the interior of plenum 42 andexits out at least one nozzle 43. The vertical height of the nozzle 43outlet is directed off-center from the container openings 17. In thisway, as a container 8 sweeps past a nozzle 42 the gas flow enters thetube by a flow path 18 and exits the container 8 by a flow path 19 aftersweeping escaped molecules from the surface of the sample 9. FIG. 6shows this external gas supply implementation with two tiers of samplecontainers 8 as discussed previously. Consequently, two tiers of nozzles43 are also required.

FIG. 7 illustrates a drying configuration for microtiter plates 48.These container array devices are familiar to those skilled in the artand may house ninety six sample cavities, each with a volume of 2.2milliliters, for example. Because a fixed 45° angle in the rotor wouldprevent the utilization of a third of the cavity volume, these containerarrays are frequently centrifuged by placing the plates in a swingingbucket 47 sitting in a horizontal position (side 44). When the spinningcarrier 4 increases in RPM, the buckets 47 swing outwards in a motionshown by arrow 45. Spinning at full speed, the bucket 47 and plate 48will assume a vertical orientation like that shown (side 46). Ablow-down gas to the sample cavities is located in an array of tubes 49just above the cavity openings and coincident with each of the openings.In this way, blow-down gas flow 18 will be produced by each of the tubesin array 49 such that the flow reaches the surface of the sample 9 inthe cavity. As before, exiting gas flow 19 is collected by centrifugalfan blades 11 and exhausted from housing by flow 20 through fitting 12and hose 13.

It should be understood that above-described embodiments are beingpresented herein as examples and that many variations and alternativesthereof are possible. Accordingly, the present invention should beviewed broadly as being defined only as set forth in the hereinafterappended claims.

1. A sample drying system comprising: a centrifuge defining a centralaxis about which the sample carrier rotates; at lest one samplecontainer, holding a sample to be dried, positioned radially withrespect to the central axis, wherein the sample container defines anopening substantially facing the central axis; a drying gas, a flowpathway for the drying gas wherein the flow pathway includes an openingproximate the central axis and an exit adjacent to the at least onesample container opening; wherein when the sample carrier is rotating,the drying gas enters the flow pathway opening and is driven radiallyalong the flow pathway to the opening of the at least one samplecontainer; wherein the drying gas is driven to the sample to be dried;wherein the drying gas picks up volatile solvent molecules and carriesthem out of the sample container.
 2. The sample drying system of claim 1wherein the flow pathway comprises a fan and a drive system, wherein therotating speed of the fan may be made different from the rotating speedof the centrifuge.
 3. The sample drying system of claim 1 furthercomprising a deflection panel located at the exit of the flow pathway,wherein the deflection panel directs the drying gas into the samplecontainer using about one half of the sample container opening.
 4. Thesample drying system of claim 1 further comprising a controlled blockagein the flow pathway wherein the volume of drying gas entering the atleast one sample container is correspondingly controlled.
 5. The sampledrying system of claim 1 further comprising controlled leakage openingsalong the flow pathway wherein the volume of drying gas entering the atleast one sample container is correspondingly controlled.
 6. The sampledrying system of claim 1 further comprising an entrance port throughwhich drying gas is introduced into the centrifuge system, and an exitport through which the drying gas and volatile solvent molecules exitthe centrifuge.
 7. The sample drying system of claim 6 wherein thevolume of drying gas entering the system is controlled to reduce dryinggas consumption with respect to the volume of drying gas and volatilesolvent molecules exiting the system, wherein the drying gas consumptionis balanced with the drying time of the sample.
 8. The sample dryingsystem of claim 5 further comprising a cold trap, wherein the drying gasand volatile molecules exit the sample drying system and enter the coldtrap, wherein the volatile molecules condense within the cold trap andthe drying gas is returned to the entrance port.
 9. The sample dryingsystem of claim 5 wherein the entrance port comprises a venturi-styleport centered such that the blow down gas enters along the central axis.10. The sample drying system of claim 1 further comprising a pluralityof sample containers distributed radially around the central axis, theplurality defining generally a first disk shaped plane about the centralaxis.
 11. The sample drying system of claim 10 further comprising atleast a second plurality of sample containers distributed radiallyaround the central axis, the at second plurality of sample containersdefining at least a second disk shaped plane about the central axis,wherein the at least a second disk shaped plane is offset axially withrespect to the first disk shaped plane, and wherein there is a flowpathway to the opening of the second plurality of sample containers. 12.The sample drying system of claim 1 wherein the at least one samplecontainer is a tube with an opening at one end, and wherein the dryinggas flow rate into the tube container is greater than 2.0 liters perminute.
 13. The sample drying system of claim 12 wherein the flow rateof the drying gas sweeps out volatile solvents but the centrifugal forceof the rotating sample carrier maintains sample yield and purity. 14.The sample drying system of claim 12 wherein the drying gas flow rateinto the tube container is between about 2.0 and about 76 liters perminute.
 15. The drying system of claim 1 wherein the at least one samplecontainer is a microtiter plate.
 16. The drying system of claim 1further comprising a second fan arranged to drive the drying gas andvolatile molecules within the sample drying system out through an exitport.
 17. A sample drying system comprising: a centrifuge defining acentral axis about which the sample carrier rotates; at least one samplecontainer, holding a sample to be dried, positioned radially withrespect to the central axis, wherein the at least one sample containerdefines an opening substantially facing the central axis; a drying gas;at least one tube section defining a flow pathways extending from anentrance port to the at least one sample container opening, the flowpathways not rotating with the sample carrier, wherein the drying gas isdriven through the flow paths and into the at least one samplecontainer, as it travels by with the rotating sample carrier, where thedrying gas picks up solvent molecules and carries them out of the atleast one sample container.
 18. The drying system of claim 17 furthercomprising a plenum with an entrance port allowing the drying gas toenter the plenum, wherein the plenum is positioned about along the axisof the centrifuge, and wherein the at least one tube section extendsfrom the plenum to the at least one sample container opening.
 19. Amethod for drying samples, the method comprising the steps of: rotatingat least one sample container around a central axis, the at least onesample container having an opening, positioning the at least samplecontainer substantially radially, wherein when the sample carrier isrotating the at least one sample container, the opening substantiallyfaces the central axis; flowing a drying gas along a flow pathway to theat least one sample container opening; flowing the drying gas to thesample to be dried; wherein the drying gas picks up volatile solventmolecules and carries them out of the sample container.
 20. The methodof claim 19 further comprising the step of controlling the volume ofdrying gas flowing into the at least one sample container.
 21. Themethod of claim 19 further comprising the step of deflecting the dryinggas with a deflection panel located at the exit of the flow pathway,wherein the drying gas enters the at least one sample container usingabout one half of the sample container opening.
 22. The method of claim19 wherein the sample container is a tube and the step of flowing thedrying gas comprises the step of flowing the drying gas at a rategreater than 2 liters per minute into the tube container.
 23. The methodof claim 19 wherein the sample container is a microtiter plate.
 24. Themethod of claim 19 further comprising the steps of introducing thedrying gas via an entrance port, and exiting the drying gas and volatilesolvent molecules via an exit port.
 25. The method of claim 24 furthercomprising the steps of: controlling the volume of drying gas enteringthe system with respect to the volume of drying gas and volatile solventmolecules exiting the system, and balancing the consumption of dryinggas used with the drying time of the sample.
 26. The method of claim 24further comprising the steps of: introducing the drying gas and volatilemolecules into a cold trap; condensing the volatile molecules within thecold trap; and recirculating the drying gas back to the sample dryingsystem.
 27. The method of claim 24 wherein the step of introducing thedrying gas comprises the step of introducing the drying gas via aventuri-type port.
 28. The method of claim 19 further comprising thestep of rotating a plurality of sample containers distributed radiallyaround the central axis, the plurality of sample containers defininggenerally a first disk shaped plane about the central axis, and whereinthere are a plurality of flow pathways to the openings of the firstplurality of sample containers.
 29. The method of claim 28 furthercomprising the step of rotating at least a second plurality of samplecontainers distributed radially around the central axis, the at leastsecond plurality of sample containers defining at least a second diskshaped plane about the central axis, wherein the at least a second diskshaped plane is offset axially with respect to the first disk shapedplane, and wherein there are a plurality of flow pathways to theopenings of the second plurality of sample containers.
 30. A method fordrying a sample, the method comprising the steps of: rotating a samplecarrier around a central axis, holding a sample to be dried in at leastone sample container that has an opening; radially positioning, withrespect to the central axis, the at least one sample container with theopening substantially facing the central axis; introducing a drying gasinto a plenum, wherein the plenum is positioned about along the centralaxis of the centrifuge; the drying gas exiting the plenum via flowpathways extending from the plenum to the at least one sample containeropening, the flow pathways not rotating with the centrifuge, wherein thedrying gas is driven through the flow paths and into the at least onesample container, as it travels by with the rotating sample carrier, andthe drying gas picking up solvent molecules and carrying them out of theat least one sample container.
 31. The method of claim 30 furthercomprising the step of condensing the volatile molecules in a cold trapand recirculating the drying gas back into the plenum.
 32. The method ofclaim 30 wherein the steps of introducing a drying gas into a plenum andexiting the plenum is replaced by a step of introducing a drying gasinto a proximate end of a tube section and delivering the drying gasfrom the distal end to the tube into the at least one sample container.